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From Wikipedia

Nitrate test

A nitrate test is a chemical test used to determine the presence of nitrate ion in solution. Testing for the presence of nitrate via wet chemistry is generally difficult compared with testing for other anions, as almost all nitrates are soluble in water. In contrast, many common ions give insoluble salts, e.g. halides precipitate with silver, and sulfates precipitate with barium.

The nitrate anion is an oxidizer, and many tests for the nitrate anion are based on this property. Unfortunately, other oxidants present in the analyte may interfere and give erroneous results.

Brown ring test

A common nitrate test, known as the brown ring test can be performed by adding iron(II) sulfate to a solution of a nitrate, then slowly adding concentrated sulfuric acid such that the sulfuric acid forms a layer above the aqueous solution. A brown ring will form at the juction of the two layers, indicating the presence of the nitrate ion. Note that the presence of nitrite ions will interfere with this test.

The overall reaction is the reduction of the nitrate ion by iron(II) which is oxidised to iron(III) and formation of a nitrosyl complex.

NO3- + 3Fe2+ + 4H+→ 3Fe3+ + NO + 2H2O
[Fe(H2O)6]2+ + NO → [Fe(H2O)5(NO)]2+

Devarda's test

Devarda's alloy (Cu/Al/Zn) is a reducing agent. When reacted with nitrate in sodium hydroxide solution, ammonia is liberated. The ammonia formed may be detected by its characteristic odor, and by moist red litmus — very few gases other than ammonia evolved from wet chemistry are alkaline.

3 NO|3|- + 8 Al + 5 OH|- + 18 H|2|O → 3 NH|3 + 8 [Al(OH)|4|]|-

The aluminium does the reducing in this reaction.

Diphenylamine test

Diphenylamine may be used as a wet chemical test for the presence of the nitrate ion. In this test, a solution of diphenylamine and ammonium chloride in sulfuric acid is used. In the presence of nitrates, diphenylamine is oxidized, giving a blue coloration. This reaction has been used to test for organic nitrates as well, and has found use in gunshot residue kits detecting nitroglycerine and nitrocellulose.

Other oxidants such as chlorate, bromate, etc. interfere by similarly oxidizing diphenylamine. They may be removed by reduction with sodium sulfite. Where nitrite is present, a false negative result may be observed due to sulfite reducing nitrate in the presence of nitrite.

The diphenylamine test may be selective for nitrate by reducing nitrite with sodium azide, prior to treatment with sodium sulfite. Other derivatives have been reported as well.

From Yahoo Answers

Question:What is the reaction for ammonium hydroxide and phenolphthalein? NH4OH + C20H14O4?? What about ammonium hydroxide + phenolphthalein + acetic acid? NH4OH + C20H14O4 + CH3COOH ? Can you also tell me what kind of reaction it is? Like single displacement, synthesis, decomposition, double displacement, neutralization, etc. Thank you so much!

Answers:Phenolphthalein reacts with bases to give a pink colour. This is because a base will take 2 protons off phenolphthalein, and the resulting ion is pink- 2NH4OH + C20H14O4 --> 2H2O + C20H12O4-- 2NH4+ This is an acid-base reaction. With ammonium hydroxide and acetic acid, they will react together to neutralise each other, creating a neutral solution, leaving phenolphthalein as the uncoloured, neutral molecule- NH4OH + C20H14O4 + CH3COOH --> H2O + CH3COONH4 + C20H14O4 This is a neutralisation reaction.

Question:a) What is the equation when 10cm3 sodium hydroxide reacts with dilute sulphuric acid until solution is neutral? b) What is the new equation when twice the volume of sulphuric acid is added? Name the new salt. c) give equations, methods and any chemicals needed to prepare i)calcium nitrate from calcium carbonate ii)calcium carbonate from calcium hydroxide (in 2 steps)

Answers:Sulphuric acid is a diprotic acid (that means it has 2 H+ that can react) therefore t undergoes two step neutralisation when reacted with NaOH 1.) NaOH + H2SO4 NaHSO4 + H2O . Please note that this reaction does not give a neutral solution, That is at pH = 7.0. The solution is still strongly acidic. But I have answered in this way in view of your second question. The salt is called sodium hydrogen sulphate 2.) NaHSO4 + NaOH Na2SO4 + H2O This is the final end point, the solution will be neutral and the quantity of H2SO4 consumed in total will be twice that consumed in the first reaction. The saltformed is called sodium sulphate 3 .1 CaCO3 +2 HNO3 Ca(NO3)2 + CO2 + H2O React 1 mol CaCO3 with 2 mol HNO3 to give Ca(NO3)2 , carbon dioxide and water 3.2 The two steps are a) Ca(OH)2 + 2CO2 Ca(HCO3)2 That is calcium hydrogen carbonate which is formed as a first step. b) This will break down on drying to give the calcium carbonate Ca(HCO3)2(aq) CO2(g) + H2O(l) + CaCO3(s).

Question:how would i write the total ionic equation and the net ionic equation to this reactionn?

Answers:Total ionic equation: HC2H3O2 + Na+ + OH- -> H2O + Na+ + C2H3O2- The acetic acid is a weak acid, so it must be written as a molecule. Sodium hydroxide is a strong base, meaning that 100% of its ions break up, so it has to be written separately. Water is a polar covalent compound, so it has to be written as a molecule. What we have left are sodium and acetate ions floating around in solution. Sodium (Na+) is the spectator ion, so if we remove this ion from both sides of the equation, we have the net ionic equation: HC2H3O2 + OH- -> H2O + C2H3O2-

Question:addition* of sodium


From Youtube

Reaction of Silver Nitrate with Sodium Hydroxide :to download this video please go to www.downloadvideos.co.nr . Sodium hydroxide solution is added to silver nitrate solution. A close up view of the reaction is shown. There is no narration.

Sodium nitrate from fertilizer and drain cleaner :This video shows the reaction of sodium hydroxide (drain cleaner) with ammonium nitrate (fertilizer). You might think that ammonium nitrate is wayyyy better than sodium nitrate. In fact this is not true: Ammonium nitrate is less suitable for redox reactions (eg black powder) and a detonation can only be achieved if you have some initial explosive, which I don t. Stay tuned for my next video: POTASSIUM nitrate from ammonium nitrate and potash!